Current connection and/or cut-off device comprising permanent contacts with reduced wear

Abstract

Device for making and/or breaking a current including a pair of permanent contacts (3, 4), at least one of the contacts (3, 4) being movable. At least one permanent contact (3, 4) including a main portion (3.1, 4.1) having a free end and an end protection portion (3.2, 4.2) secured to the free end of the main portion (3.1, 4.1), designed to be in mechanical and electrical contact with the other permanent contact (4, 3) only during an operation for opening or closing the pair. The end protection portion (3.2, 4.2) is made of a single transition metal having a melting temperature that is strictly higher than that of the main portion (3.1, 4.1) to which it is secured, or of an oxide or carbide of such a metal, or even of zinc oxide. For application in particular to high- or medium-voltage circuit breakers.

What is claimed is: 
     
       1. A device for making and/or breaking a current, the device comprising:
 a pair of permanent contacts, at least one of the permanent contacts of the pair of permanent contacts being movable; 
 a pair of arcing contacts, at least one of the arcing contacts being movable; 
 a closed position wherein the arcing contacts are in mechanical and electrical contact with each other, and wherein the permanent contacts are in mechanical and electrical contact with each other; 
 an open position wherein the arcing contacts are not in mechanical nor in electrical contact with each other, and wherein the permanent contacts are not in mechanical nor in electrical contact with each other; 
 wherein the arcing contacts and the permanent contacts are configured so that, during a transition from the closed position to the open position of the device, the electrical contact between the permanent contacts is broken before the electrical contact of the arcing contacts; and 
 wherein at least one permanent contact of the pair of permanent contacts comprises a main portion having a free end and an end protection portion secured to the free end of the main portion, the end protection portion being designed to be in mechanical and electrical contact with the other permanent contact of the pair of permanent contacts only during an operation for opening or closing the pair of permanent contacts, said end protection portion being made of a single transition metal, said transition metal having a melting temperature that is higher than that of the main portion to which it is secured, or of an oxide of such a metal, or of a carbide of such a metal, or of zinc oxide. 
 
     
     
       2. The device for making and/or breaking the current according to  claim 1 , wherein the main portion is made of copper, of copper alloy, or of aluminum, or aluminum coated in silver, and the transition metal is chosen from: tungsten, molybdenum, cobalt, titanium, zirconium, chromium, or nickel. 
     
     
       3. The device for making and/or breaking the current according to  claim 1 , wherein the end protection portion is a coating at a surface of the free end of the main portion. 
     
     
       4. The device for making and/or breaking the current according to  claim 3 , wherein the coating has a thickness within a range of about 50 μm to 300 μm. 
     
     
       5. The device for making and/or breaking the current according to  claim 1 , wherein the main portion is formed of a plurality of successive elements assembled to one another, one of which elements forms the free end of the main portion. 
     
     
       6. The device for making and/or breaking the current according to  claim 1 , wherein the end protection portion is an endpiece fastened by screw-fastening or adhesive to the free end of the main portion. 
     
     
       7. The device for making and/or breaking the current according to  claim 6 , wherein the endpiece is monolithic. 
     
     
       8. The device for making and/or breaking the current according to  claim 1 , wherein the permanent contact provided with the end protection portion comprises a hollow cylinder. 
     
     
       9. The device for making and/or breaking the current according to  claim 1 , wherein the permanent contact provided with the end protection portion comprises a collar provided with a plurality of fingers. 
     
     
       10. The device for making and/or breaking the current according to  claim 1 , wherein the device is a circuit breaker, a disconnector, a switch, or a contactor. 
     
     
       11. A device for making and/or breaking a current, the device comprising:
 a pair of permanent contacts, at least one of the permanent contacts of the pair of permanent contacts being movable; 
 a pair of arcing contacts, at least one of the arcing contacts being movable; 
 a closed position wherein the arcing contacts are in mechanical and electrical contact with each other, and wherein the permanent contacts are in mechanical and electrical contact with each other; 
 an open position wherein the arcing contacts are not in mechanical nor in electrical contact with each other, and wherein the permanent contacts are not in mechanical nor in electrical contact with each other; 
 wherein the arcing contacts and the permanent contacts are configured so that, during a transition from the closed position to the open position of the device, the electrical contact between the permanent contacts is broken before the electrical contact of the arcing contacts; and wherein at least one permanent contact of the pair of permanent contacts comprises a main portion having a free end and an end protection portion secured to the free end of the main portion, the end protection portion being designed to be in mechanical and electrical contact with the other permanent contact of the pair of permanent contacts only during an operation for opening or closing the pair of permanent contacts, said end protection portion being designed so that, in the closed position of the device, the end protection portion is separated from the other permanent contact of the pair of permanent contacts, and said end protection portion being made of a single transition metal, the transition metal having a melting temperature that is strictly higher than that of the main portion to which it is secured, or of an oxide of such a metal, or of a carbide of such a metal, or of zinc oxide.